What behavior are you seeing?  Does your news server return an error
message?

Still waiting for clarification on this.

I tried to cancel an article and it simply doesn't happen anything. No
error message of the server or anything else, just the message
continued beeing in the newsgroup.

My Version is the 0.11.2

If you didn't get any message, chances are the cancel was successful.

Next time you cancel a message, empty the group and get all headers
again.  I'm pretty sure your message will be gone: although Pan
cancels the message on the news server, it doesn't actually delete the
message locally. 

It would probably be clearer for the user if it did. :-)

Chris, do you want to put a mesage in the log and/or a popup dialog?

Done, although I suspect this may actually be a bug after all.

I've noticed that sometimes cancelling doesn't work. Instead, we get
the following assertion failure on the console:

pan-CRITICAL **: file article-actions.c: line 196 (article_cancel):
assertion `is_nonempty_string (newsgroups)' failed.

What's happening is that article_get_extra_header() fails to retrieve
the newsgroup field, because a->headers is NULL.  Seems like sometimes
the extra headers hash isn't getting populated ?

I'd like to keep this report open a while longer to investigate this.

*** This bug has been marked as a duplicate of 71992 ***

Whoops!  I was trying to hit "go to bug #", not "mark as duplicate"

*** Bug 73915 has been marked as a duplicate of this bug. ***

Fixed in CVS.